Contact bounce mitigator

ABSTRACT

A beveled spring plate is disposed between the stationary contact and mounting panel of an electrical contactor. A similar plate is connected in reverse manner between the rear of the mounting panel and a bolt from the stationary contact member. The assembly is compressed snugly by the bolt. Impact forces provided by contact closure are dampened by compression of the front plate and rebound forces are similarly dampened by compression of the rear plate.

United States Patent lnventor Jerome F. Dries Waukesha, Wis. Appl. No. 878,357 Filed Nov. 20, 1969 Patented June 15, 1971 Assignee Cutler-HammerJnc.

Milwaukee, Wis.

CONTACT BOUNCE MITIGATOR 5 Claims, 3 Drawing Figs.

(1.8. CI 200/166 Int. Cl. H0lh 1/50 Field of Search 200/166 H; 335/193 56] References Cited UNITED STATES PATENTS 1,807,815 6/1931 White 335/193 3,129,308 4/1964 Yokoyama et al ..200/l66 (H) (X) 3,214,559 10/1965 Kesselring et al. 200/166 (H) 3,503,019 3/1970 Kussy etal 335/193 Primary Examiner-H. 0. Jones Attorney- Hugh R. Rather ABSTRACT: A beveled spring plate is disposed between the stationary contact and mounting panel of an electrical contactor. A similar plate is connected in reverse manner between the rear of the mounting panel and a bolt from the'stationary contact member. The assembly is compressed snugly by the bolt. lmpact forces provided by contact closure are dampened by compression of the front plate and rebound forces are similarly dampened by compression of the rear plate.

PATENTED JUNI 5mm 3 535 332 sum 2 or 2 Jig Z 34 CONTACT BOUNCE MITIGATOR BACKGROUND OF THE INVENTION This invention relates to electrical switching devices and more particularly to a contactbounce mitigator therefor.

One of the problems in electrical switching devices, particularly those of large' current capacity, is in reducing contact bounce. The contacts must close rapidly to prevent arcing, and large closing forces are designed for this purpose. As the closing forces increase, the resulting rebound, or bounce forces also increase which tends to open the contacts and again create an arc. Therefor, it is necessary to provide some means to absorb the impact and rebound forces to prevent contact bounce upon closure of the contacts of an electrical device to eliminate the arcing and resultant contact welding that occurs.

SUMMARY OF THE INVENTION It is therefor the primary object of this invention to provide means for absorbing the impact of rebound forces present between two members when one member closes upon the other to mitigate the bounce between the two members.

It is another object of this invention to provide means for mounting a stationary contact of an electrical switching device which will absorb the impact and rebound forces present upon contact closure to mitigate the contact bounce, said means being relatively easy and inexpensive to manufacture.

It is a further object of this invention to provide means for mitigating the contact bounce of an electrical switching device which may be readily applied to devices of different designs.

These and other objects and advantages of the invention will become more readily apparent in the following specification and claims when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view, partially in cross section, showing an electrical contactor incorporating the contact bounce mitigator of this invention;

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1; and

FIG. 3 is an exploded isometric view of the parts comprising the bounce mitigator of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The contact bounce mitigator of this invention is shown applied to a DC magnetic contactor in FIG. 1 of the drawings. The contactor comprises a frame assembly 2 having an insulating mounting panel 4 secured thereto by a plurality of bolts 6 and cooperating nuts 8.

A magnet frame 10 and core 12 assembly are secured to the mounting panel 4 by bolt means (not shown) near the lower end of the panel. A coil 14 is disposed over the core 12 and secured thereon by a retaining clip 16. An armature assembly 18 is pivotally mounted at the outer end ofthe magnet frame 10 by bearing pin means 20 to pivot into engagement with core 12.

Armature assembly 18 carries a movable contact assembly 22 at its free end. Movable contact assembly 22 includes a contact arm 24 which is pivotally attached to armature 18 by a pivot pin 26, a contact member 28 secured to arm 24 by bolt means 30 and a spring 32 biasing-said contact assembly in a clockwise direction about pivot pin 26 on the armature assembly 18.

A U-shaped stationary contact mounting post 34 is secured to the mounting panel 4 by bolts 36 and 38 to project forwardly over the magnet assembly. A stationary contact 40 is rigidly attached to the mounting post 34 by means 42 to be in cooperating alignment with movable contact 28. A magnetic blowout coil 44 is provided within the U-shaped mounting post 34, the coil extending between leftand right-hand arc shields 46 (only one of which is shown) and. having connections to an arc horn 48. The details of the arc quenching features of the contactor formv no part of this :invention and one of which is inserted between the lower leg of post 34 and the panel 4 and the other of which is rotated therefrom, reversed, and placed between the rear of panel 4 and the head of bolt 38 A spring pin 52 is pressed into a hole in panel 4 to extend in opposite directions therefrom through clearance holes 54 in spring plates 50 to maintain the assembly in proper alignment. The front plate 50 is positioned as shown to gain horizontal stability for the contact post 34 while the rear plate 50 is rotated 90to permit the utilization of the same plate instead of two individual plates. A U-shaped insulator 56 is interposed between the rear of panel'4 and the rear plate 50 to provide additional electrical insulation around the metal spring plate 50 in the proximity of mounting frame 2.

The upper leg of contact post 34 is rigidly secured to mounting panel 4 by bolt 36 and the lockwasher arrangement therewith. Bolt 38 is not provided with a lockwasher, but instead has a nylon pellet 58 imbedded in the threaded shank to project slightly therefrom. When bolt 38 is turned into tapped hole 60 in post 34, the pellet 58 is cut and compressed between the mating threads to hold the bolt 38 at whatever depth it is turned into hole 60. This depth may vary according to the various thickness and type of material chosen for plates 50 and the amount of contact closing force to be mitigated. However, in the particular installation shown, the bolt 38 is turned in to compress the plates 50 flat and is then backed out one-half turn to relax the spring plates 50 somewhat. The drawings have been exaggerated in this respect to more clearly show the invention.

In operation, the magnet coil 14 is energized to attract armature 18 thereto, carrying with it the movable contact 28 which closes upon the stationary contact 40 against the bias of spring 32. The force imparted by contact 28 striking against the contact 40 is transmitted to the lower leg of post 34 to compress the from spring plate 50 against the mounting panel 4, thereby providing a somewhat resilient cushion for the contact pair 28 and 40. The thin cross section of the upper leg of post 34 permits the post to flex somewhat to provide the movement of the lower leg relative to the upper leg. The natural rebound force which occurs after closing is similarly mitigated by compression of rear plate 50 between the insulator 56 and the head of bolt 38. While the rigid mounting and relatively large mass of contact post 34 tend to absorb some of the impact and rebound forces imparted by contact closure, the use of the mitigator of this invention has been found to reduce contact bounce time by 40 percent. The application of the mitigator is not intended to be limited to the contactor described herein, but only by the scope of the appended claims.

I claim:

1. In an electrical switching device comprising; in combination;

an insulating base member;

stationary contact means mounted on said base member;

movable contact means mounted for movement relative to said base member and said stationary contact means; means for moving said movable contact means into electrical engagement with said stationary contact means; and means for absorbing the impact and rebound forces to mitigate the contact bounce between said movable and stationary contact means upon closure of the former upon the latter comprising; I first and second plate members each having one opposite pair of beveled edges forming an offset central portion, said first plate member disposed between said stationary contact means and said base member, and said second plate member disposed on the opposite side of said base member from said first plate member;

aligned apertures in said first and second plate members and said base member; and

threaded fastener means extending through said aligned apertured and connecting the outer surface of said second plate means and said stationary contact means to maintain said first and second plate members partially compressed.

2. The combination according to claim 1 wherein said second plate member is reversed with respect to said first plate member to have the offset portion of each of said first and second plate members spaced from said base member.

3. The combination according to claim 2 wherein said second plate member is rotationally displaced from said first plate member to have the said one opposite pair of beveled edges thereof displaced at right angles to the said beveled edges of said first plate member.

4. The combination according to claim 3 wherein each plate member has another aperture and pin means are provided in said base member to extend in opposite directions therefrom to cooperate with the last-mentioned apertures to position said first and second plate members as aforedescribed.

5. The combination according to claim 3 wherein said stationary contact means includes a branch leg portion rigidly secured to said base member at a point remote from said means for absorbing the impact and rebound forces. 

1. In an electrical switching device comprising; in combination; an insulating base member; stationary contact means mounted on said base membEr; movable contact means mounted for movement relative to said base member and said stationary contact means; means for moving said movable contact means into electrical engagement with said stationary contact means; and means for absorbing the impact and rebound forces to mitigate the contact bounce between said movable and stationary contact means upon closure of the former upon the latter comprising; first and second plate members each having one opposite pair of beveled edges forming an offset central portion, said first plate member disposed between said stationary contact means and said base member, and said second plate member disposed on the opposite side of said base member from said first plate member; aligned apertures in said first and second plate members and said base member; and threaded fastener means extending through said aligned apertured and connecting the outer surface of said second plate means and said stationary contact means to maintain said first and second plate members partially compressed.
 2. The combination according to claim 1 wherein said second plate member is reversed with respect to said first plate member to have the offset portion of each of said first and second plate members spaced from said base member.
 3. The combination according to claim 2 wherein said second plate member is rotationally displaced from said first plate member to have the said one opposite pair of beveled edges thereof displaced at right angles to the said beveled edges of said first plate member.
 4. The combination according to claim 3 wherein each plate member has another aperture and pin means are provided in said base member to extend in opposite directions therefrom to cooperate with the last-mentioned apertures to position said first and second plate members as aforedescribed.
 5. The combination according to claim 3 wherein said stationary contact means includes a branch leg portion rigidly secured to said base member at a point remote from said means for absorbing the impact and rebound forces. 